85_wood

Pollution Prevention and Abatement Handbook
Industry Description and Practices
and the treated wood storage areas. Some of themajor pollutants present in drips, surface runoff,
Wood preserving involves imparting protective
and contaminated soil include polynuclear aro-
properties to wood to guard against weathering
matic hydrocarbons, pentachlorophenol, pesti-
and attack by pests. Three main types of preser-
cides, dioxins, chrome, copper, and arsenic.
vatives are used: water based (for example, so-dium phenylphenoxide, benzalconium chloride,
Pollution Prevention and Control
guazatin, and copper chrome arsenate); organicsolvent based (for example, pentachlorophenol
Wood preserving involves different combinations
and such substitutes as propiconazol, tebuco-
of a wide variety of processes, and there are many
nazol, lindane, permethrin, triazoles, tributyltin
opportunities to improve on the traditional prac-
compounds, and copper and zinc naphthenates);
tices in the industry. The following improvements
borates; and tar oils (such as creosote). Note that
should be implemented where feasible.some of the preservatives mentioned here (for example,lindane, tributyltin, and pentachlorophenol) are
• Do not use pentachlorophenol, lindane,
banned in some countries and are not to be used.
tributyltin, or copper chrome arsenate (or its
The preservatives are applied to the surface of
wood by pressure impregnation, with a pressure
• Give preference to pressurized treatment pro-
range of 800 kilopascals (kPa) to 1,400 kPa; by
cesses to minimize both wastage of raw materi-
deluging (mechanical application by flooding or
als and the release of toxics that may be present.
spraying), by dipping or immersion; and by ther-
• Minimize drippage by effective removal of
mal processing (immersion in a hot bath of pre-
extra preservative from the wood surface by
servative). Application of vacuum helps to
mechanical shaking until no drippage is no-
improve the effectiveness of the process and to
ticeable. Provide sufficient holding time af-
recover some of the chemicals used. Pesticides
ter preservative application to minimize free
are applied using appropriate protective cloth-
ing, including gloves, aprons, overalls, and in-
• Recycle collected drips after treatment, if
• Heat treated wood when water-based preser-
Waste Characteristics
• Use concrete pads for the wood treatment area
Any or all of the substances used in wood pre-
serving, such as preservatives and solvents, can
proper collection of drippage. Treated wood
be found in the drips and the surface runoff
should be sent for storage only after drippage
streams. Air emissions of solvents and other vola-
tile organics result from the surface treatment
• Minimize surface runon by diversion of
steps, drying of the treated wood, and storage
stormwater away from the process areas.
and transfer of chemicals. Soil contamination
• Cover process areas and collect surface runoff
may result from the drippage and surface run-
for recycling and treatment. Where water-
off, and this may happen near the process areas
based preservatives are used, prevent freshly
PROJECT GUIDELINES: INDUSTRY SECTOR GUIDELINES
treated wood from coming into contact with
ronmental assessment (EA) process on the basis of
country legislation and the Pollution Prevention and
• Sites should be selected that are not prone to
Abatement Handbook, as applied to local conditions.
flooding or adjacent to water intake points or
The emissions levels selected must be justified in
the EA and acceptable to the World Bank Group.
• Preservatives and other hazardous substances
The guidelines given below present emissions
should be stored safely, preferably under a roof
levels normally acceptable to the World Bank
Group in making decisions regarding provision
• Proper labels should be applied, and used
of World Bank Group assistance. Any deviations
packaging should be returned to the supplier
from these levels must be described in the World
for reuse or sent for other acceptable uses or
Bank Group project documentation. The emis-
sions levels given here can be consistentlyachieved by well-designed, well-operated, and
Target Pollution Loads
well-maintained pollution control systems.
The guidelines are expressed as concentrations
Minimize contamination of surface runoff and
to facilitate monitoring. Dilution of air emissions
soil. Have a closed system for managing liquids
or effluents to achieve these guidelines is un-
to avoid the discharge of liquid effluents.
All of the maximum levels should be achieved
Treatment Technologies
for at least 95% of the time that the plant or unitis operating, to be calculated as a proportion of
Exhaust streams should be treated, using carbon
filters that allow the reuse of solvents, to reducevolatile organic compounds (VOCs) to acceptable
The maximum air emission level from wood im-
levels before venting to the atmosphere. Where
pregnation areas for VOC is 20 milligrams per
VOC recovery is not feasible, destruction is carried
out in combustion devices or bio-oxidation systems.
Wood-preserving plants should use closed sys-
The main treatment process is recycling of col-
tems, where feasible, or should attain the efflu-
lected drips and surface runoff after evaporation.
Other processes include detoxification (using ul-traviolet oxidation) and precipitation or stabili-
Wherever possible, generation of sludges and
contaminated soil should be minimized. Con-taminated soil and sludges must be treated, sta-
Contaminated soil may contain heavy metals and
bilized, and disposed of in an approved, secure
toxic organics and should normally be managed
landfill. The levels of toxics in the leachate should
as hazardous waste. Treatment methods include
be the same as for liquid effluents.
incineration of toxic organics and stabilization ofheavy metals.Emissions Guidelines
Noise abatement measures should achieve eitherthe levels given below or a maximum increase in
Emissions levels for the design and operation of
background levels of 3 decibels (measured on the
each project must be established through the envi-
A scale) [dB(A)]. Measurements are to be taken
Table 1. Effluents (Including Surface Runoff)
operating standards so that any necessary correc-
from the Wood-Preserving Industry
tive actions can be taken. Records of monitoring
results should be kept in an acceptable format. Theresults should be reported to the responsible au-
thorities and relevant parties, as required.Key Issues
The key production and control practices that will
lead to compliance with emissions guidelines can
• Do not use pentachlorophenol, lindane,
tributyltin, copper chrome arsenate, or other
preservatives that are considered toxic and for
which less toxic alternatives are available for
• Use pressurized treatment processes.
• Heat treated wood when water-based preser-
Note: Effluent requirements are for direct discharge to surface
• Minimize drippage carryover by ensuring that
drippage has completely stopped before re-
at noise receptors located outside the project
area. Collect and recycle drip solutions, andput in place total recycle systems for liquids
• Use concrete pads for the wood treatment and
• Divert stormwater away from process areas.
• Recycle solvent vapors, where feasible; other-
wise, they should be destroyed in a combus-
tion device or in a bio-oxidation system.
• Manage contaminated soil and sludges as haz-
Monitoring and Reporting
Daily monitoring of the parameters listed in this
United States. 1990. “Wood Preserving; Identification
document, except for metals, should be carried
and Listing of Hazardous Waste: Final Rule.” Fed-
out to provide an indication of overall treatment
eral Register, vol. 55, no. 235, December 6.
reliability. Metals should be sampled at least
World Bank. 1995. “Industrial Pollution Prevention and
monthly. More frequent sampling may be re-
Abatement: Wood Preserving Industry.” Draft Tech-
quired for certain batches and during wet
nical Background Document. Environment Depart-
Monitoring data should be analyzed and re-
viewed at regular intervals and compared with the

For Faces Almost Lost to History, a Chance to Speak The 19th and 20th centuries saw the invention of a lot of new ways to do away with people. But the same 200 years ensured that more people might be remembered, thanks to new recording devices, photography most of all. Many who might once have completely disappeared from view now leave behind visible traces of themselves. But what do these